Amantadine hydrochloride (1-adamantanamine hydrochloride), which is considered to be the most important agent presently available for the prevention and treatment of viral infections caused by influenza type A viruses, exhibits serious central nervous system (CNS) side effects, such as inability to concentrate, nervousness and insomnia, and drowsiness in the host. While these CNS effects are not the sole cause of the commercial failure of the drug (and the subsequent decrease in research and development activity in the area of antivirals), they have significantly contributed to the general non-acceptance of amantadine hydrochloride by the medical profession. Thus, there is a need for an antiviral agent exhibiting prophylactic and therapeutic activity similar to that of amantadine without the CNS effects associated with this first generation drug to not only provide physicians with an alternative to or conjunctive with immunoprophylaxis, but also to stimulate further research in the prevention and treatment of viral infectious disease. See, for example, T. H. Maugh III, Science, 192, 128 (1976), G. G. Jackson and E. D. Stanley, J. Am. Med. Assoc. 235, 2739 (1976) and A. Chanin, J. Am. Med. Assoc., 237, (1977 ).
Providing an antiviral agent having a spectrum of activity closely related to that of amantadine free of CNS side effects would be a significant advance in the art.